You do have my highest respect and gratitude! I live in NC and was thrilled to see this great model made for a great NC landmark. And congrats for winning the competition, of course!
The top rails weren't so easy to assemble. Pre-bending it before gluing did the trick. I believe you also built in a spare rail for gluing/backing up? I ended up cutting it off.
The string trick came to me after numerous taping attempts had failed. I majored in Math; in geometry the shortest line between two points on a curvature (thus naturally formed by tightening a string between them) is called a geodesic. Believe it or not, this is a central concept in Einstein's General Theory of Relativity: our space-time is not flat but has a curvature caused by the existence of mass, and all objects including light naturally move along geodesics in this curvature, thus giving the appearance of gravity:) I'm pretty sure too this is how the real lighthouse was painted: just drop four cables from top, pull real hard at bottom, then paint along them!